Pressure operated arming mechanism



United States Patent Ofiice 3,362,333 Patented Jan. 9, 1968 ABSTRACT OF THE DISCLOSURE A fluid pressure actuated arming mechanism for an ordnance tfuze having a generally cylindrical slider normally held in the unarmed position by a pair of pivotallymounted, spring-biased locking arms engaging opposing flats cut in the slider. The locking arms are disengaged by application of fluid pressure to pistons which act on the locking arms against the spring bias. Once the locking arms have been disengaged, the slider is free to move. The slider is moved to the armed position by application of fluid pressure to a piston which acts on the slider. Movement of the slider "to the armed position either aligns an explosive train or closes a set of electrical contacts.

Background of the invention This invention generally relates to arming devices for ordnance fuzes, and more particularly to a fluid pressure actuated arming mechanism for an ordnance fuze having specific application to a drop bomb or missile propelled through the air.

In the past, it has been the practice to provide power to operate an arming device for an ordnance fuze from some source of stored energy such as, for example, a battery. Self-contained power supplies have a number of limitations including deterioration in storage, problems in activation, and bulk to name a few. Recently, with the advent of fluidics, it has been proposed to employ pure fluid delay devices operated by ram air during the free fall of a bomb or the flight of a missile, as the case may be, in the fuze arming mechanism. Specifically, a pure fluid binary counter might be used as the delay device and would produce a fluid pressure output after a predetermined period of time. This, of course, has the advantage of eliminating the need of a stored power supply; however, the output from a rarn-air operated pure fluid device is quite low. Heretofore, there has not been available a suitable mechanism for reliably converting these low fluid pressures to a precise mechanical displacement as would be required in a practical arming device for an ordnance fuze.

It is therefore an object of the instant invention to provide a mechanism for producing a precise mechanical displacement in response to a low pressure fluid signal such as that generated by a ram-air operated pure fluid device.

It is another object of this invention to provide an arming mechanism for an ordnance fuze which mechanism is capable of reliable operation by a low pressure fluid signal.

Summary According to the present invention, the foregoing and other objects are attained in an arming mechanism for an ordnance fuze which converts a low pressure fluid pressure signal to a mechanical displacement by providing a generally cylindrical slider that is prevented from moving from an initially unarmed position by two spring biased arms which engage opposing flats formed on the slider. The locking aims are released by application of fluid pressure to piston elements mounted on the arms. Once released, the slider is free to move in response to a fluid pressure applied to a piston element attached to the slider. Low pressure operation is attained by the provision or diap'hragms between the source of fluid pressure signals and each of the piston elements thereby eliminating leakage.

Brief description of the drawings The specific nature of the invention, as well as other objects, aspects, uses, and advantages thereof, will clearly appear from the following description and from the accompanying drawing, in which:

FIGURE 1 is a plan view, partially in cross-section, of the preferred embodiment of an arming mechanism accor-ding to the invention;

FIGURE 2 is a cross-section of the mechanism taken along section line 22 of FIGURE 1; and

FIGURE 3 is a cross-section of the mechanism taken along section line 33 of FIGURE 1.

Description of the preferred embodiment Referring now to the drawing wherein like reference numerals designate identical or corresponding parts throughout the several views, the preferred embodiment according to the invention has a body 4 which, for purposes of illustration, has a cylindrical shape. Body 4 may take any convenient shape that might be dictated by volume requirements of the particular application. It is preferably made of some light material such as aluminum or thermoplastic or thermo-setting resin composition. A stepped bore 6 is formed in body 4 perpendicular to the longitudinal axis thereof. A cylindrical slider 8 having a hole Ill bored therethrough perpendicular to its longitudinal axis is slidably disposed in bore 6. Slider 8 is provided with an alignment pin (not shown) which extends into a longitudinal slot cut part way along the length of bore 6. The purpose of this pin is .to maintain hole 10 in proper alignment. Slots 17 and 17a each mutual-1y perpendicular to the longitudinal axis of body 4 and bore 6 are formed in either face of body 4 and extend a short distance into bore 6. A pair of rigid locking arms 14 and 16 are pivotally mounted within slots 17 and 17a, respectively. More particularly, one end 18 of arm 14 is bent around a radius to form a hinge eye through which pin 15 passes. In like manner, end 20 of arm 16 is made to form a hinge eye through which pin 19 passes. Pins 15 and 19 are secured in the respective sidewalls of slots 17 and 17a diametrically opposite one another on either side of bore 6. Thus mounted, locking arms 14 and 16 can move in an arcuate path away from slider 8 but are normally biased by springs 21 and 23, respectively, into a pair of opposing flats 22 and 24 cut in slider 8 when the latter is in its unarmed position. This arrangement pro motes the safety of the mechanism by making it highly resistant to shock. Any force impulse due to shock will act in the same direction on both locking arms. Thus, while one of the locking arms may be driven out of en gagement with its respective flat in slider 8, the other will be driven so as to promote engagement. 7

With slider 8 locked in the unarmed position by the engagement of locking arms 14 and 16 in flats 22 and 24, hole 10 is maintained in an out-of-line position with respect to a passageway 26 extending through body 4 perpendicular to bore 6. Passageway 26 is in line with the firing pin and explosive train of the associated fuze. In its unarmed position, slider 8 is therefore effective to obstruct passageway 26 rendering the fuze safe. Arming occurs when slider 8 is displaced in bore 6 to a point where hole 10 and passageway 26 are in registry.

Piston elements 27 and 27a are fixedly attached to the free ends 26 and 28, respectively, of locking arms 14 and 16. While piston elements 27 and 27a are shown as separate elements, it is to be understood that they may be integral with arms 14 and 16 and may simply be a broadened area at the free ends 26 and 28 thereof. In any event, piston elements 27 and 27a are of low mass to insure fast response of the mechanism. Slots 1.7 and 170 are enlarged at one end to accommodate piston elements 27 and 27a resulting in the slots generally resembling keyholes. Fluid passageways 34 and 36 are drilled through body 4 into the enlarged portions of slots 17 and 1711, respectively, perpendicular to the faces of piston elements 27 and 27a. Direct communication, however, between fluid in passageways 34 and 36 and piston elements 27 and 27a is prevented by flexible, expanding diaphragms 29 and 29a which seal the outlets of passageways 34 and 36, respectively, and upon which piston elements 27 and 27a rest. Fluid from a common source such as the output of a pure fluid binary counter is transmitted to passageways 34 and 36 by way of pressed fittings 3t} and 32, respectively.

When fluid pressure in passageways 34 and 36 increases, diaphragms 29 and 29a expand against the faces of piston elements 27 and 27a forcing locking arms 14- and 16 outward against the bias of springs 21 and 23 thereby disengaging flats 22 and 24 and releasing slider 8. Mechanical advantage is obtained by having the free ends 25 and 28 of locking arms 14 and 16 extend a greater distance beyond bore 6 than do pivoted ends 18 and 20. Though not to scale, the drawings show a multiplication factor of approximately 2 to l.

A piston element 39 is fixedly attached to the end of slider 8 which extends into the enlarged portion of stepped bore 6. The enlarged portion of stepped bore 6 opens into a larger diameter hole 44 Which has a portion of its sidewall cut away to form a slot. A flexible, expanding diaphragm 38 is sealingly attached to the interior of body 4 at the shoulder formed between stepped bore 6 and hole 44. Fluid is applied to diaphragm 38 via fitting 42 pressed into circular plug 48 and passageway 46 formed in plug 48. Plug 48 is held in hole 44 by a circular retaining member 52 threaded into hole 44.

Once the locking arms 14 and 16 have been disengaged from flats 22 and 24, an increase in fluid pressure in passageway 46 which may be caused by a second fluid signal from a pure fluid binary counter will cause diaphragm 38 to expand against piston element 39 and drive slider 8 into the armed position as shown by the phantom line in FIGURE 1. To further increase the safety of the mechanism, undercut lips 47 and 49 are formed on flats 22 and 24, respectively, to prevent camming of the locking arms 14 and 16 by a premature pressure signal applied to diaphragm 38 before the locking arms have been released. Locking arms 14 and 16 may, in addition, be beveled to mate with undercut lips 47 and 49 to further decrease the possibility of camming. When in the armed position, a portion 56 formed on the end of slider 8 protrudes through an opening 58 formed in body 4 at the end of bore 6 and positively retained there by a pair of spring steel fingers 57 and 59 riveted on body 4 and extending partially over opening 53.

Obviously, many modifications and variations of the present invention are possible in the light of the above teachings. For example, the displacement of slider 8 may be used to toggle an electric switch rather than align an explosive train as particularly described. It is therefore to be understood, that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.

What is claimed and desired to be secured by Letters Patent of the United States is:

1. A fluid pressure actuated arming mechanism for an ordnance fuze, comprising:

a body having a bore formed therein, said body addi tionally having a pair of slots formed therein perpendicular to and on either side of said bore and extending a short distance into said bore,

a generally cylindrical slider slideably disposed within said bore and having opposing flats formed thereon,

a pair of pivotally-mounted, spring biased locking arms positioned within respective ones of said slots normally engaging said opposing flats on said slider thereby locking said slider in the unarmed position,

a pair of piston elements in contact with respective ones of the free ends of said locking arms,

a pair of flexible, expanding diaphragms sealingly mounted within respective ones of said slots, said piston elements normally resting on said diaphrarns.

means for delivering a first fluid pressure signal to the side of said pair of diaphragms opposite said piston elements thereby causing said diaphragms to expand against the faces of said piston elements forcing said locking arms outward against their spring bias whereby said loclting arms are made to disengage said flats and release said slider,

a piston element in contact with said slider,

a flexible, expanding diaphragm sealingly mounted within said bore adjacent said piston element,

means for delivering a second fluid pressure signal to the side of said diaphragm opposite said piston element thereby causing said diaphragm to expand against the face of said piston element and displacing the same to its armed position once said locking arms have been disengaged.

2. A fluid pressure actuated arming mechanism for an ordnance fuze as recited in claim 1 further comprising:

means for engaging said slider and locking the same in position once it has been displaced to its armed position.

3. A fluid pressure actuated arming mechanism for an ordnance fuze as recited in claim 1 wherein said body additionally has a passageway formed therein perpendicular to said bore through which a firing pin in an explosive chain may pass, and wherein said slider has a hole formed therein which, when said slider is in its armed position, is in registry with said passageway, said slider otherwise acting to obstruct said passageway.

No references cited.

BENJAMIN A. BORCHELT, Primary Examiner.

G. H. GLANZMAN, Assistant Examiner. 

